Engine dies then OK

My '79 KZ1000B is having a problem with the engine cutting out. Actually, I am having the problem with it.

When I'm riding, the engine suddenly dies and the bike comes to a stop. Once in awhile it starts up again while the bike is still rolling. If not, within a few seconds I can start the motor and be on my way.

At first I thought it was fuel but I just cleaned the carbs and the tank is more than half full. Today I made a round trip of 4 miles and the engine died five or six times.

So I figure it's a grounding issue. When the engine dies the lights stay on. I'm guessing these possible suspects:

1) Kill switch wiring needs cleaning.

2) Key on ignition switch is turning ever so slightly to the "park" position and turning off the motor.

3) Power to coils is disrupted (maybe #1 above)?

Once when the bike was rolling to a halt today I got it into neutral, held the clutch in and pushed the starter button. The starter didn't turn over, even though the lights were on. A few seconds later the starter turned over.

No matter what this issue is, I will clean the contacts on the ground wire going to the motor, once it cools off.

Any suggestions how to tackle this?

Thanks, Mike

The Dreaded Shorting/Intermittent Electrical Problem!


Here is the most basic method I know(Taken from www.kzrider.com by member Patton)

1. Charge your battery and have it load tested if you can. The floating ball hydrometer can be used to check the specific gravity of the charged cells in the battery.

2. Disconnect the Black lead from the (-) Battery terminal... or Red from the (+) Battery terminal, it does not matter which one.

3. Connect one of the following test setups in series with the Battery terminal and lead:
3.1 A 12 V light bulb,
3.2 A 12 V test light,
3.3 A 12 V test buzzer or,
3.4 A 12 V horn... you get the idea.

4. With the Ignition Switch OFF, go through your harness and wiggle the wires while looking/listening for the test setup to go on/start buzzing.

5.With the Ignition Switch ON, repeat the test except this time the looking/listening for the test setup to go off/stop buzzing.

6. Be prepared to open the Ignition switch and check/test for solder joint failure and or circuit board micro breaks (don't ask how I know this ).

7. Be prepared to pull the wires out of the Head Light to test for failures at or near the grommet.

8. Be prepared to open the harness at or near the Steering Neck for failures. This is where wires tend to exhibit fatigue due to repetitive movement.

9. Be prepared to open the left and right switch gear to search for rust and or broken parts. CAUTION: watch out for flying springs, ball bearings and stuff. Do indoors on White sheet (again don't ask ).

10. Be prepared to follow the heavy gauge wire from the Starter Solenoid (Relay) to the starter for bare wire exposure. Especially near bends and grommets.

11. If you can reproduce the fault symptom your are pretty much home free. Be prepare to find and repair/replace any internal wire breaks, insulation break downs, exposed wires, rubber grommet failures, etc. Often, shrink tubing will solve the problem temporarily until something better can be done.

12. I use a very good electrical contact cleaner/preservative called De-oxit made by Caig Labs in San Diego Ca. Their website is www.deoxit.com It can be purchased at Radio Shack and any other electronic supply store. I use it on all of my motorcycle’s electrical connectors , in my home entertainment center’s stereo patch cords and cordless phones charging cradles.


Your problem may be loose battery cables,a fuse or two going bad, or an ignition switch that's getting worn out.

I follow almost everything in your post. The first part - disconnect the battery, then put in a test light/horn something like that connected to the positive and negative leads? I think that's what you're saying.

The rest of the stuff I've been through before. Earlier this year I put together a CB550 Honda and everything you could imagine was wrong with the wiring harness. Hacked wires by an old owner, shot starter switch, corroded leads etc. Then when I got it running, a dowel was missing from the stator cover and the stator was a little off center. It slightly rubbed on the rotor and the stator fried in minutes. The starter solenoid also died and within a few miles of having the engine running right the original headlight died too.

Well that's all behind me now and this KZ1000 is in much better shape. Just this intermittent electrical thing started happening a lot today and I need to figure it out.

Thanks!

These kinds of things are hard to diagnose. When I'm worried about a possible intermittent spark issue I hook up a timing light and take it for a ride. that way you can tell at what RPM, heat level, and exact conditions that are making the spark cut out. Just go driving along and when the timing light cuts out then the spark is gone.

If not already done, would double-check integrity of all fuses and their connections.

And also assure integrity of ground connection from the i.c. igniter.

Good Fortune!

Check your fuel line to make sure it isn't pinched or kinked.

Thanks for all the helpful tips. Now I have a new problem. This morning I went outside and found the #1 spark plug wire ripped to shreds! Likely culprit pictured below.
He's only nine months old so he likes to chew stuff. Like the wood boards pictured in the background. Brutus is keeping me busy!

Well I ordered some new wires from Z1 Enterprises today. And I will get busy with the wiring gremlin soon.

Also I picked up a motorcycle cover from the local cycle shop today. My two other bikes have covers and Brutus doesn't mess with them.

Your problem could very well be an intermittent ground. I had a similar problem on my '75 Z1 last summer. Turned out to be the single pin bullet coupler off the left handlebar control harness under the fuel tank. Thankfully it finally stayed off long enough so I could track it down. Intermittent problems can drive you nuts. Hope you find it.

I think it's fixed! Lucky I had an extra plug wire around to replace the one Brutus ate.

Next I removed the tank, headlight and left sidecover. Checked the bullet connectors, cleaned them and disconnected/reconnected the plastic connectors in the headlight shell. Also removed the battery ground wire, cleaned the connection and replaced.

For awhile something was not right. No spark going to the plugs (and this was not a problem yesterday). I rechecked the connections to the coils and the Dyna ignition, then there was a spark.

One other odd thing. As I was doing this, the neutral light and stop light on the dashboard quit working for awhile. And the two turn signal indicators on the dash turned on. Then once the bike started, the turn signal indicators turned off.

So I disconnected the wiring in the headlight shell, noting the terminals appeared corroded. I had already sprayed them with electrical contact cleaner. So I scraped them with an exacto knife (hard to get in there), cleaned and reassembled.

Now the lights worked correctly and the bike started fine. I rode about 10 miles and no more intermittent failures. So far so good!

same thing was happening to me and i found a bad wire going into stator cover, musta been pinched inside the insulation but u could nt see it, discovered it by luck when the bike quit and i pulled off the road, reached down and shazam, wiggled it and power returned, i think it may have gotten pinched when someone put the cover back on and didnt get the wire in the slot correctly